Tory Matteson has retained his lead at the John Deere Classic after a second-round 68, but has seen his advantage reduced to one shot.
Matteson had surged three shots clear after the first round, but a sparkling round of 62 from Jeff Maggert has seen him remain ahead by just a solitary shot heading into the weekend.
Maggert's 62 took him to 12-under for the tournament, where he is joined in second place by Brian Harman, who recorded a second successive round of 65.
England's Gary Christian is part of a group of four players a further shot back, as he looks to record his first top-10 finish on the PGA Tour.